It is a known fact that wires, such as electrically insulated winding wires for use in the manufacture of electrical devices, must have a good sliding capacity so that they car be positioned easily and accurately when windings are being manufactured. In addition, the sliding capacity of the wire should protect the electrically insulated layer during machining.
Various methods are known for imparting a sliding capacity to wires. Paraffins are predominantly used as lubricants, and they are applied as a coating in the form of solutions in benzene or other organic solvents through a felt onto the wire which is usually still warm. The solvent is vaporized, and a thin layer of paraffin remains behind on the surface of the wire. However, this method of application employs solutions with 1/2 to 1% proportions of paraffin, which causes high losses of solvent and thus economic losses and considerable harm to the air.
With another known method, instead of solutions of paraffin in benzene or other organic solvents, aqueous emulsions or dispersions of paraffins are used. This prevents the emission of organic solvents, but the way in which the emulsion is metered using wick or felt is problematical. A method like this is therefore unsuitable, if, as often desired, very precisely defined quantities of paraffin have to be applied to the surface of the wire. In addition, if aqueous emulsions are used, an additional drying operation is required.
All the previously known methods where the lubricant has been applied to the wire by the use of felt also have the drawback that the felt rubs off from the wires after prolonged use, and often no recognition is taken of the fact that since the felt has been rubbed off, the lubricant is only applied to one side, or not at all.
Accordingly, there is still a need in the art to overcome the drawbacks of the known methods for imparting a sliding capacity to wires, and in particular, to arrive at a method which is simple, reliable, and avoids solvent emissions.